Bug 1452618 - track force-disabling things so we don't accidentally re-enable them by using `isUsableAddon` later, r=kmag

MozReview-Commit-ID: B7ZAw04cVaZ

--HG--
extra : rebase_source : f5349905640c1c7403c11df9370f9a38c1d35584

toolkit/mozapps/extensions/internal/XPIProvider.jsm

@@ -811,6 +811,11 @@ function isUsableAddon(aAddon) {
     return false;
   }
 
+  // If we can't read it, it's not usable:
+  if (aAddon.brokenManifest) {
+    return false;
+  }
+
   // Experiments are installed through an external mechanism that
   // limits target audience to compatible clients. We trust it knows what
   // it's doing and skip compatibility checks.

toolkit/mozapps/extensions/internal/XPIProviderUtils.js

@@ -1320,6 +1320,7 @@ this.XPIDatabaseReconcile = {
         manifest = syncLoadManifestFromFile(file, aInstallLocation);
       } catch (err) {
         // If we can no longer read the manifest, it is no longer compatible.
+        aOldAddon.brokenManifest = true;
         aOldAddon.appDisabled = true;
         return aOldAddon;
       }

toolkit/mozapps/extensions/test/xpcshell/test_upgrade_incompatible.js

@@ -8,7 +8,7 @@ add_task(async function test_upgrade_incompatible() {
 
   createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "1.9.2");
 
-  await promiseStartupManager();
+  await promiseStartupManager(false);
 
   let file = createTempWebExtensionFile({
     manifest: {
@@ -51,5 +51,26 @@ add_task(async function test_upgrade_incompatible() {
   equal(addon.appDisabled, true);
 
   await promiseShutdownManager();
+
+  file = createTempWebExtensionFile({
+    manifest: {
+      applications: {gecko: {id: ID}},
+    },
+  });
+
+  // swap the old extension back in and check that we don't persist the disabled state forever.
+  await OS.File.move(file.path, path);
+  await promiseSetExtensionModifiedTime(path, timestamp);
+  Services.obs.notifyObservers(new FileUtils.File(path), "flush-cache-entry");
+
+  // Restart.  With the change to the DB schema we recompute compatibility.
+  Services.prefs.setIntPref("extensions.databaseSchema", 0);
+  await promiseStartupManager(true);
+
+  addon = await promiseAddonByID(ID);
+  notEqual(addon, null);
+  equal(addon.appDisabled, false);
+
+  await promiseShutdownManager();
 });